These studies are assessing the growth and nutritional status of children with sickle cell disease (SCD) and will examine the interaction of these parameters with clinical status. Although the growth deficits of SCD patients have been previously described, the longitudinal course of their growth failure and its relationship to nutritional and disease related factors are not understood. We hypothesize that deficits in height and weight, and delayed skeletal and sexual maturation result from three factors: 1) the effects of increased energy demand in the steady state; 2) the additional energy demand of acute vaso-occlusive complications; and 3) low nutritional intake associated with poor appetite. Poor appetite is frequently reported by mothers of SCD patients, but the nutritional intakes of SCD patients have not been well documented. Furthermore, the energy cost of SCD has never been fully assessed. In this set of related studies we are: 1) evaluating longitudinally the growth, nutritional status, and body composition of 150 SCD patients; 2) assessing energy expenditure of SCD patients in a healthy state, during an acute SCD complication, and following treatment with hydroxyurea; and 3) determining the dietary intakes and nutritional needs of children with SCD. The findings of these studies will provide guidelines for the nutritional needs of patients with SCD and determine the degree to which nutritional intervention can improve and positively affect the clinical course of SCD.